scholarly journals On the Kinematics of Solar Mirrors Using Massively Parallel Binary Actuation

2010 ◽  
Author(s):  
Seung J. Lee ◽  
Amy M. Bilton ◽  
Steven Dubowsky
Keyword(s):  
Experimental Studies ◽  
Analytical Models ◽  
Massively Parallel ◽  
Thermal Gradients ◽  
Two Dimensional ◽  
Principle Of Superposition ◽  
Element Analysis ◽  
Solar Concentrators ◽  
One Dimensional ◽  
Binary Actuators

Precision mirrors are required for effective solar energy collectors. Manufacturing such mirrors and making them robust to disturbances such as thermal gradients is expensive. In this paper, the use of parallel binary actuation to control the shape of mirrors for solar concentrators is explored. The approach embeds binary actuators in a compliant mirror substructure. Actuators are deployed in a specified pattern to correct the mirror shape. The analysis for binary-actuated compliant mirror structures is presented. Analytical models are developed for one-dimensional and two-dimensional compliant structures with embedded binary actuators. These analytical models are validated using finite element analysis and experimental studies. The models and experiments demonstrate the capabilities of binary actuated mirrors. System workspace is explored, the principle of superposition required for their control is demonstrated, as is the mirror ability to correct its figure.

scholarly journals FFT for the APE Parallel Computer

1997 ◽  
Vol 08 (06) ◽  
pp. 1317-1334 ◽  
Author(s):  
Thomas Lippert ◽  
Klaus Schilling ◽  
Sven Trentmann ◽  
Federico Toschi ◽  
Raffaele Tripiccione
Keyword(s):  
Systolic Array ◽  
Parallel Computer ◽  
Massively Parallel ◽  
Two Dimensional ◽  
One Dimensional ◽  
Data Field ◽  
Matrix Transposition ◽  
Neighbor Connectivity ◽  
Parallel Fft ◽  
Parallel Fft Algorithm

We present a parallel FFT algorithm for SIMD systems following the "Transpose Algorithm" approach. The method is based on the assignment of the data field onto a one-dimensional ring of systolic cells. The systolic array can be universally mapped onto any parallel system. In particular for systems with next-neighbor connectivity our method has the potential to improve the efficiency of matrix transposition by use of hyper-systolic communication. We have realized a scalable parallel FFT on the APE100/Quadrics massively parallel computer, where our implementation is part of a two-dimensional hydrodynamics code for turbulence studies.

scholarly journals Nonlinear processes in the bunched electron beams of high-power klystrons and the limits of analytical and one-dimensional numerical models applicability for their analysis.

2020 ◽  
Vol 2020 (12) ◽  
Author(s):  
V.Y. Rodyakin ◽  
◽  
V.M. Pikunov ◽  
V.N. Aksenov ◽  
◽  
...  
Keyword(s):  
Electron Beam ◽  
High Power ◽  
Numerical Models ◽  
Nonlinear Effects ◽  
Analytical Models ◽  
Modulation Amplitude ◽  
Two Dimensional ◽  
One Dimensional ◽  
Charge Parameter ◽  
Program Data

We present the results of a comparative theoretical analysis of the electron beam bunching in a single-stage klystron amplifier using analytical models, a one-dimensional disk program, and a two-dimensional program. Data on the influence of various one-dimensional and two-dimensional nonlinear effects on the efficiency of electron beam bunching at different values of the space charge parameter and the modulation amplitude are presented. The limits of applicability of analytical and one-dimensional numerical models for electron beam bunching analysis in high-power klystron amplifiers are found.

Piezoelectric Modal Sensors for Two-Dimensional Structures

Aerospace ◽  
2004 ◽  
Author(s):  
Yuan-Fang Chou ◽  
Ming-Yi Yang
Keyword(s):  
Finite Element Analysis ◽  
Free Surface ◽  
Signal Strength ◽  
Mode Shapes ◽  
Two Dimensional ◽  
Surface Charges ◽  
Optimization Scheme ◽  
Element Analysis ◽  
One Dimensional ◽  
Orthogonal Property

Using the orthogonal property of eigenfunctions, piezoelectric modal sensors for one-dimensional members were created by shaping electrode patterns proportional to modal strains. However, it is not easy to apply the same concept to two-dimensional structures due to the difficulty in implementing location weight needed for signals. Therefore, nonlinear optimization scheme is employed in this paper to design modal sensors for two-dimensional structures. For a given electrode pattern, the signal contributed from each mode is found by integrating the corresponding free surface charges on the sensing electrode. Then the modal sensor is obtained by modifying electrode pattern to achieve required relative signal strength for different modes. Sensors that are capable to sense or filter out the signal generated by a specific mode can be developed. A two-dimensional aluminum plate coated with PZT layer is adopted as an example. Mode shapes are found with finite element analysis. Modal sensors are designed successfully and mode- reject filters are also demonstrated.

Finite Element Analysis of the Lift on a Slightly Deformable and Freely Rotating and Translating Cylinder in Two-Dimensional Channel Flow

1999 ◽  
Vol 121 (2) ◽  
pp. 148-152 ◽  
Author(s):  
Y. Zhao ◽  
M. K. Sharp
Keyword(s):  
Finite Element ◽  
Flow Field ◽  
Channel Flow ◽  
Experimental Studies ◽  
Angular Speed ◽  
Two Dimensional ◽  
Lateral Migration ◽  
Flexible Cylinder ◽  
Element Analysis ◽  
Maximum Deformation

Motivated by the lateral migration phenomena of fresh and glutaraldehyde-fixed red blood cells in a field flow fractionation (FFF) separation system, we studied the transverse hydrodynamic lift on a slightly flexible cylinder in a two-dimensional channel flow. The finite element method was used to analyze the flow field with the cylinder at different transverse locations in the channel. The shape of the cylinder was determined by the pressure on the surface of the cylinder from the flow field solution and by the internal elastic stress. The cylinder deformation and the flow field were solved simultaneously. The transverse lift exerted on the cylinder was then calculated. The axial and angular speed of the cylinder were iterated such that the drag and torque on the cylinder were nulled to represent a freely translating and rotating state. The results showed that the transverse lift on a deformable cylinder increased greatly and the equilibrium position moved closer to the center of the channel compared to a rigid cylinder. Also, with the same elastic modulus but a higher flow rate, a larger deformation and higher equilibrium location were found. The maximum deformation of the cylinder occurred when the cylinder was closest to the wall where a larger shear rate existed. The numerical results and experimental studies are discussed.

Transient response of an erodable heat flux gauge using finite element analysis

2002 ◽  
Vol 216 (8) ◽  
pp. 701-706 ◽  
Author(s):  
D R Buttsworth
Keyword(s):  
Heat Flux ◽  
Finite Element ◽  
Surface Temperature ◽  
Transient Response ◽  
Transient Heat Conduction ◽  
Two Dimensional ◽  
Element Analysis ◽  
Ic Engine ◽  
One Dimensional ◽  
Transient Heat Flux

The transient response of an erodable ribbon element heat flux gauge has been assessed using a two-dimensional finite element (FE) analysis. Such transient heat flux gauges have previously been used for measurements in internal combustion (IC) engines. To identify the heat flux from the measurements of surface temperature, it is commonly assumed that the heat transfer within these devices is one-dimensional. A corollary of the one-dimensional treatment is that only one value of the thermal product, , is needed for identification of the transient heat flux, even though erodable heat flux gauges are constructed from at least two different materials. The current results demonstrate that two-dimensional transient heat conduction effects have a significant influence on the surface temperature measurements made with these devices. For the ribbon element gauge and timescales of interest in IC engine studies, using a one-dimensional analysis (and hence a single value of ) will lead to substantial inaccuracy in the derived heat flux measurements.

The influence of lateral spreading on settlements beneath a fill

1994 ◽  
Vol 31 (2) ◽  
pp. 145-150
Author(s):  
C.B. Crawford ◽  
H. Jitno ◽  
P.M. Byrne
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Close Agreement ◽  
Lateral Spreading ◽  
Two Dimensional ◽  
Element Analysis ◽  
Vertical Movements ◽  
One Dimensional ◽  
Dimensional Finite Element ◽  
Earth Embankment

The discrepancy between calculated consolidation settlements and measured settlements under a 3.8 m high section of an earth embankment is investigated in this paper. A conventional one-dimensional analysis underestimated the observed settlement by 40%. A two-dimensional finite-element analysis was carried out to assess the effects of lateral spreading on vertical movements, and the results were in close agreement with the measured values. Key words : case history, consolidation, finite element analysis, settlement.

scholarly journals Synthesis, Properties, and Applications of Low-Dimensional Carbon-Related Nanomaterials

2011 ◽  
Vol 2011 ◽  
pp. 1-21 ◽  
Author(s):  
Ali Mostofizadeh ◽  
Yanwei Li ◽  
Bo Song ◽  
Yudong Huang
Keyword(s):  
Carbon Nanotubes ◽  
Carbon Nanomaterials ◽  
Experimental Studies ◽  
Structural Features ◽  
Two Dimensional ◽  
One Dimensional ◽  
Synthesis Properties ◽  
Carbon Nanowalls ◽  
Low Dimensional ◽  
Carbon Encapsulated Metal Nanoparticles

In recent years, many theoretical and experimental studies have been carried out to develop one of the most interesting aspects of the science and nanotechnology which is called carbon-related nanomaterials. The goal of this paper is to provide a review of some of the most exciting and important developments in the synthesis, properties, and applications of low-dimensional carbon nanomaterials. Carbon nanomaterials are formed in various structural features using several different processing methods. The synthesis techniques used to produce specific kinds of low-dimensional carbon nanomaterials such as zero-dimensional carbon nanomaterials (including fullerene, carbon-encapsulated metal nanoparticles, nanodiamond, and onion-like carbons), one-dimensional carbon nanomaterials (including carbon nanofibers and carbon nanotubes), and two-dimensional carbon nanomaterials (including graphene and carbon nanowalls) are discussed in this paper. Subsequently, the paper deals with an overview of the properties of the mainly important products as well as some important applications and the future outlooks of these advanced nanomaterials.

Vibration Localization in Near-Periodic Coupled Two-Dimensional Resonator Arrays

2005 ◽  
Author(s):  
John A. Judge ◽  
Joseph F. Vignola ◽  
Brian H. Houston ◽  
Douglas M. Photiadis ◽  
Martin H. Marcus
Keyword(s):  
Statistical Investigation ◽  
Two Dimensional ◽  
Energy Propagation ◽  
Element Analysis ◽  
One Dimensional ◽  
Dimensional Array ◽  
Vibration Localization ◽  
Filter Performance ◽  
Localization Theory ◽  
Effects Of Disorder

The effects of small deviations from periodicity on the vibration behavior of coupled arrays of mechanical resonators are investigated, and the consequences for energy propagation across such arrays are described. Existing localization theory is applied to demonstrate that one-dimensional arrays designed as bandpass filters are particularly sensitive to aperiodicity when narrow passband requirements dictate weak inter-resonator coupling. A novel two-dimensional array of resonators is proposed that is less sensitive to disorder than one-dimensional arrays, improving filter performance without the need for improved manufacturing tolerances. Numerical simulations of a simple model are employed to demonstrate the effects of disorder on one- and two-dimensional arrays, and a case study design is discussed that includes statistical investigation using finite-element analysis and experimental measurements of a prototype two-dimensional array.

The Effect of Weak Interface on Transverse Properties of a Ceramic Matrix Composite

1989 ◽  
Vol 170 ◽  
Author(s):  
R. A. Shimansky ◽  
H. T. Hahn ◽  
N. J. Salamon
Keyword(s):  
Composite System ◽  
Experimental Studies ◽  
Ceramic Matrix Composite ◽  
Interfacial Bonding ◽  
Analytical Models ◽  
Interface Debonding ◽  
Nasa Lewis Research ◽  
Element Analysis ◽  
Transverse Stiffness ◽  
Transverse Tensile

AbstractExperimental studies conducted at the NASA Lewis Research Center on silicon carbide reaction-bonded silicon nitride composite system (SiC/RBSN) led to a significant observation regarding their unidirectional tensile properties. It was found that transverse stiffness and strength were much lower than those predicted from existing analytical models based on good interfacial bonding. Since the composite system was designed to have weakened interfaces to improve toughness, it was believed that these weakened interfaces were responsible for the decrease in transverse properties.To support this claim, a two dimensional finite element analysis was performed for a transverse representative volume element. Specifically, the effect of fiber/matrix displacement compatibility at the interface was studied under both tensile and compressive transverse loadings. Interface debonding was represented active gap elements connecting the fiber and matrix.The analyses show that the transverse tensile strength and stiffness are best predicted when a debonded interface is assumed for the composite. In fact, the measured properties can be predicted by simply replacing the fibers by voids. Thus, the following two conclusions are drawn from the present study: (1) little or no interfacial bonding exists in the SiC/RBSN composite; (2) an elastic analysis can predict the transverse stiffness and strength.

Semi-Analytical Models of Field-Effect Transistors with Low-Dimensional Channels

2011 ◽  
Vol 276 ◽  
pp. 51-57
Author(s):  
A. Kohmyakov ◽  
V. Vyurkov
Keyword(s):  
Field Effect ◽  
Potential Distribution ◽  
Field Effect Transistors ◽  
Silicon On Insulator ◽  
Analytical Models ◽  
Double Gate ◽  
Two Dimensional ◽  
One Dimensional ◽  
The Poisson Equation ◽  
Low Dimensional

A semi-analytical model which is applicable to description of ballistic field-effect transistors with low-dimensional channels is proposed. For instance, such transistors can be manufactured on a “silicon-on-insulator” wafer. The model accounts for single-gate and double-gate structures with one-dimensional and two-dimensional channels. It differently describes the regimes of a transistor above threshold and below threshold. The first implies an essential influence of charge inside the channel on a potential distribution; the second supposes a negligible charge inside the channel. Both approaches are mainly based upon an approximate solution of the Poisson equation.

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